Cored carbon with arc-extinguishing plug.



W. R. MOTT.

00am CARBON WITH ARC EXTlNGUiSHING PLUG.

APPLICATION FILED DEC. 26, 1911. 1 18mm PatentedJune13, 1916.

WITNESSES ATTORNEY IQE.

WILLIAM ROY MOTTJOF LAKEWOOD, OHIO, ASSIGNOR TO NATIONAL CARBON CO., OF

CLEVELAND, OHIO, .A CORPORATION OF NEW JERSEY.

" ORED CARBON WITH ARC-EXTINGUISHING PLUG.

Specification of Letters Patent.

Patented Junel 191%.

Application filed December 26, 1911. Serial No. 667,822. 4

To all whom it may" concern:

Be it known that I, lVILLiAM ROY MOTT, a resideat of Lakewood, in the countv of Cuyahoga, in the State of Ohio, have invented new and useful Improvements in Cored Carbons with Arc-Extinguishing Plugs, of which the following is a clear and exact description.

This invention is an improvement in cored carbons with are extinguishing plug. As is well .known, cored carbons consist of an outer part that is formed with a central channel. The carbon and channel are formed at the same time by forcing a carbon mix out through a die in a hydraulic press machine. The carbons are then dried and baked to obtain the requisite hardness, and finally are ready to be filled with the material to enrich the flame of the arc. This material is forced into the hollow in the carbon by pressure and frequently the workman removes the carbon before it is filled to the tip. The defective carbons must either be thrown on the scrap heap or else additional time and labor must be expended to patch them up. Then again the carelessness of the workman frequently. results in air bubbles being formed within the core. In the defective cores the air bubbles cause the candle power to vary or even'cause the disruption of the are.

In case the binding materialis of an insulating nature when coldythe-end of the core cannot be plated satisfactorily when the carbon is silver tipped.

\Vhen lamps are used in series across a.-

constant voltage circuit, it frequently happens that the lamps will not break the circuit when the carbons are burned down to the point where this action should take place. The lamp sometimes continues to burn until the econoinizer or other part is burned out. This results from the high conductivity of the are due to the material in the core.

My invention obviates the fore-mentioned ditficulties in the manner clearly stated in the following description, particular'reference being had to the drawings in which;

Figure 1 is a section through the length of a cored carbon, showing my improve ment atthched thereto. Fig. 2 shows a section of a cored carbon with. a modified arrangement. Fig. 3 shows a section of a carbon with another modified arrangement.

Referring to Fig. l, the outer part of the carbon is designated by reference character 1. The inner part, or core, is designatedby 2. A plug 3 fills the holder end of the car bon. This plug or rod is of slightly less diameter than the hole in the carbon 1, and is approximately two and one-half inches long,

this being the usual length of the end that is ultimately thrown away as a stub. The plug is inserted by hand in a freshly filled carbon, and pressed in for about a half-inch. After it has set for about-a half minute the workman holds a finger overthe flame end of the carbon and pushes the plug to place. By this process the material is densely packed within, and if the carbon is not entirely filled the material will be forced to the extreme tip. It is therefore not necessary to go through a separate process for patching up defective tips. If there are any air bubbles in the core, it becomes evident when the plug 3 is pressed in, as the core is elastic and partly forces the plug outward when the pressure is released. defective carbon is thrown on the scrap heap as the air bubble cannot be eliminated satisfactorily. My invention thus aids in the de tection of defective carbons. The plug 3 may also be inserted by a machine. In case it were inserted mechanically the plug would U be forced out slightly by any. air bubbles when the carbon was removed from the machine so that a defective carbon could be detected. The carbon 1 and plug 3, having none of the enriching materials that are found in the core filling, will. not-support an arc of any great length. The result is that when the carbon burns down to the plug 8 the lamp will go out, thus avoiding the difliculty previously mentioned. It will beimpossible for the arc to continue to burnafter the filling material is. all burned out, as the length of arc is greater than can be maintained without this material. The plug 3 may be of material similar to the outer part 1, and is a good conductor of electricity when cold. Hence the entire end of the carbon will be coated with metal in the silver tipping process. The material in the plug is'cheaper than that used in the core. In a twenty-four inch carbon the plug takes up approximately 10% of the space. My improvement therefore results in a saving of expensive filling material.

It is obvious that the upper stub eud of When this happens the I 

